Removal of some KAUTH_GENERIC_ISSUSER (pass 1)

Hi,
Attached is a diff removing some KAUTH_GENERIC_ISSUSER uses in favor of
more meaningful alternatives, some newly added.
Newly added actions/requests:
- KAUTH_MACHDEP_CMOS, for checking if the CMOS can be read
from/written to.
- KAUTH_MACHDEP_CACHEFLUSH_ALL, for checking if the whole CPU cache
can be flushed (used in compat code only).
- KAUTH_REQ_SYSTEM_SYSCTL_MODIFY, for checking if a sysctl(9) value
that doesn't have a custom function handler can be modified.
- KAUTH_REQ_NETWORK_SOCKET_DROP, for checking if a connection can be
dropped.
- KAUTH_REQ_NETWORK_SOCKET_SETPRIV, for checking if privileged
socket options can be set.
Also note the changes in the ibcs2 compat code. I followed
http://docsrv.sco.com:507/en/man/html.S/uadmin.S.html and hopefully the
semantics are the same.
Thanks,
-e.